In the art devices with dual light transmitting members for producing spot to flood configurations of reflected radiant energy are well known. Devices of this general nature have, for example, been disclosed in U.S. Pat. Nos. 1,862,276, 2,712,060, 1,768,613, 1,875,607 and 2,155,752. In Pat. No. 2,712,060 there is disclosed a device designed for use on an aircraft body and arranged to provide for producing remote control of a spot to flood configuration of reflected rays of light. In this device a pair of Fresnel type light transmitting members are mounted in front of a lamp and reflector body with one of the Fresnel type light transmitting members being rotatable with respect to the other.
Each of the light transmitting members of this patent contains Fresnel lens portions extending across the light transmitting members in parallel relation to one another. When the Fresnel lens portions are perfectly mated with one another, a spot configuration is produced. To produce a flood configuration, one of the light transmitting members must be rotated with respect to the other and, before this can be done, one light transmitting member must be axially displaced with respect to the other. This is objectionable since it produces an immediate discontinuity in the adjustment from spot to flood. In addition, the axial displacements of light transmitting members will make the device quite susceptible to accumulation of foreign matter between the light transmitting members, which will interfere with proper mating of the lens parts when adjusted for a spot configuration.
A second prior art disclosure which also describes a dual light transmitting system, in which one light transmitting member is rotatable with respect to another, is set forth in U.S. Pat. No. 2,848,601. In this device the light transmitting members are constructed with sectors having refracting portions by means of which a variance between spot and flood configurations may be realized. However, in this device, alternate sectors are constructed with annuloid lens portions, while the intervening refracting sectors are constructed with lens portions which extend radially outwardly from the center. With this arrangement the lens portions must again be perfectly mated to produce satisfactory spot configuration.
The need for axial displacement of one light transmitting member before rotation may be carried out is present in this device as well, and thus the same objections as those already noted with respect to U.S. Pat. No. 2,712,060 are present
In addition, neither of these prior art devices can provide for configurations of light distribution between the extremes of spot and flood in which illumination of areas peripheral to the spot may be provided in a predetermined and controlled configuration.